Method of forming multilayer coating film made from natural material

ABSTRACT

Disclosed are a multilayer coating film made from a natural material and a method of producing the same. The multilayer coating film may be produced by forming a multilayer coating film through formation of a color coating film for providing adhesion and color to a cork on the cork material and a clear coating film for realizing texture and supplementing properties on the color coating film. As such, the multilayer coating film may be made from a natural material to diversify the color and gloss of cork as a natural material, to additionally increase marketability of an interior material and provide various appearance, to prevent discoloration due to light (e.g. UV light.) and water permeation, and to enhance durability against abrasion, scratches and the like.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims under 35 U.S.C. § 119(a) the benefit of priorityto Korean Patent Application No. 10-2015-0180128 filed on Dec. 16, 2015,the entire contents of which are incorporated herein by reference.

BACKGROUND (a) Technical Field

The present invention relates to a method of forming a multilayercoating film made from a natural material. For example, the method maycomprise forming a color coating film for providing adhesion and colorto a cork of a substrate, and forming a clear coating film for providingtexture and supplementing properties on the color coating film, therebymanufacturing the multilayer coating film on the substrate comprisingthe cork. As such, the multilayer coating film made from a naturalmaterial, e.g. cork, may diversify the color and gloss from a naturalmaterial (the cork), and additionally increase marketability of aninterior material and provide various exteriors. In addition, themultilayer coating film may prevent discoloration due to light (e.g. UVlight.) and water permeation, and enhance durability against abrasion,scratches, and the like.

(b) Background Art

Recently, materials including components containing real wood has beenused to provide sophistication, luxuriousness, and the like to theexteriors of vehicles. For example, in the process of producing theinterior materials containing the real wood, a base to be covered with awood material is first laid as a base layer and then the base is coveredwith the real wood, followed by coating/polishing a surface of the realwood as a finishing process. Through the coating/polishing, the surfaceof the real wood becomes smooth and glossy and, at the same time, visualluxuriousness like wood grain may be obtained.

Cork typically provides excellent insulation, noise insulation, electricinsulation, elasticity and the like with luxuriousness, which is one ofthe characteristics of a natural material. In addition, the cork removessuperior volatile organic compounds (VOC), discharges far-infraredradiation, deodorizes, and has antibacterial function and the like.Accordingly, the cork has been used instead of conventional real woodmaterials.

However, such natural cork may be epidermis of a cork oak and a softmaterial, scratch resistance, abrasion resistance, and the like thereofmay be weak. In addition, since natural cork is a wood material, it maybe susceptible to discoloration by light or deformation by moisture.

Accordingly, when the natural cork is used under severe conditions as invehicle components, a coating may be required to the surface of thenatural cork. With regard to this surface-coating, there is a need forresearch into preventing discoloration of the natural cork due to light(e.g. UV light.) without surface luxuriousness decrease of the naturalcork and enhancing durability such as scratch and abrasion resistanceand gloss.

The above information disclosed in this Background section is only forenhancement of understanding of the background of the invention andtherefore it may contain information that does not form the prior artthat is already known in this country to a person of ordinary skill inthe art.

SUMMARY OF THE INVENTION

The present invention has been made in an effort to solve theabove-described problems associated with the prior art.

Inventors of the present invention confirmed that a multilayer coatingfilm was formed by forming a color coating film for providing adhesionand color to a cork on the cork material and forming a clear coatingfilm for realizing texture and supplementing properties on the colorcoating film.

The term “cork”, as used herein, refers to a material obtained from awooden bark tissue, without particular limitation to tree species,manufacturing processes, or other chemical and physical propertiesthereof.

The term “color coating film”, as used herein, refers to a coating filmor a coating layer comprising one or more of layers that may contains apigment reflecting or transmitting a fraction of light as the result ofwavelength-selective absorption, such that the color coating film can bedetected by a naked eye to have the reflected color by the pigment. Assuch, the color coating film may reflect the light in the wavelengthdepending on the pigment therein. For example, the color coating filmmay reflect or transmit the visible light in the range of about 300 to800 nm, or 400 to 700 nm, which includes color ranges from red toviolet. In addition, the color coating film may reflect or transmitvarious visible light wavelengths depending on the combination ofpigments without limitation. The color coating film may entirely orpartially reflect or transmit of about 10% or greater, of about 20% orgreater, of about 30% or greater, of about 40% or greater, of about 50%or greater, of about 60% or greater, of about 70% or greater, of about80% or greater, of about 90% or greater, of about 95% or greater, or ofabout 99% or greater of the absorbed visible light.

The term “clear coating film”, as used herein, refers to a coating filmor a coating layer comprising one or more of layers that may betransparent or substantially transparent. As such, the clear coatingfilm may entirely or substantially transmit a fraction of light such asvisible light having a wavelength in the range of about 300 to 800 nm.For instance, substantial amount of visible light such as, at least ofabout 50%, at least about 60%, at least about 70%, at least about 80%,at least about 90%, at least about 95%, or at least about 99% thereofmay transmit or pass through the clear coating film of the presentinvention.

As such, the color and gloss of cork as a natural material may bediversified, a marketability may additionally increase from an interiormaterial, the interior material may have various appearances,discoloration due to light (UV light, and the like) and water permeationmay be prevented, and durability against abrasion, scratches, and thelike may be enhanced.

In preferred aspects, the present invention provides a multilayercoating film made from a natural material such as a cork and a method ofproducing the same, thereby preventing discoloration due to light, waterpermeation, and the like of the cork material and providing durabilitywhile diversifying the color and gloss of the cork material.

In one aspect, the present invention provides a multilayer coating filmmade from a natural material. Preferably, the multilayer coating filmmay comprise a natural cork material including a base layer, a non-wovenfabric layer, and a cork layer. In an exemplary embodiment, themultilayer coating film may comprise: a base layer, a non-woven fabriclayer, and a cork layer that may comprise a color coating compositionand a clear coating composition. In particular, the color coatingcomposition may be coated on the cork layer to form a color coating filmand the clear coating composition may be coated on the color coatingfilm to form a clear coating film. The color coating composition maycomprise a waterborne polyurethane resin, a waterborne acrylic resin, acoloring pigment, a wetting agent, a defoaming agent, a hardeningaccelerator, a light stabilizer, a thickener, and a solvent, and theclear coating composition may comprise an acrylic resin, a polyesterpolyol, a reaction catalyst, a wetting additive, a light stabilizer, aquencher, a hardener, and a solvent.

Preferably, a thickness of the color coating film may be of about 5 to10 μm and a thickness of the clear coating film may be of about 25 to 35μm.

Preferably, the color coating composition may comprise an amount ofabout 30 to 50% by weight of the waterborne polyurethane resin, anamount of about 10 to 30% by weight of the waterborne acrylic resin, anamount of about 0.3 to 5% by weight of the coloring pigment, an amountof about 0.1 to 1.0% by weight of the wetting agent, an amount of about0.1 to 2.0% by weight of the defoaming agent, an amount of about 0.01 to1.0% by weight of the hardening accelerator, an amount of about 0.5 to5.0% by weight of the light stabilizer , an amount of about 0.1 to 3.0%by weight of the thickener, and an amount of about 5 to 30% by weight ofthe solvent, all the % by weight based on the total weight of the colorcoating composition.

Preferably, the clear coating composition may comprise an amount ofabout 20 to 40% by weight of the acrylic resin, an amount of about 5 to15% by weight of the polyester polyol, an amount of about 0.1 to 1.5% byweight of the reaction catalyst, an amount of about 0.1 to 1.0% byweight of the wetting additive, an amount of about 1.0 to 2.0% by weightof the light stabilizer, an amount of about 1.0 to 5.0% by weight of thequencher, an amount of about 10 to 20% by weight of the hardener, and anamount of about 25 to 30% by weight of the solvent, all the % by weightbased on the total weight of the clear coating composition.

For the color coating composition, the waterborne polyurethane resin maycomprise an amount of about 20 to 40% by weight of a solid content basedon the total weight of the waterborne polyurethane resin, and thewaterborne polyurethane resin has pH of about 6 to 10.

Preferably, the waterborne polyurethane resin may comprise an amount ofabout 5 to 30% by weight of isocyanate, an amount of about 2 to 10% byweight of hydrophilic polyol, an amount of about 30 to 60% by weight ofpolycarbonate diol, an amount of about 5 to 25% by weight of a solvent,and an amount of about 1 to 5% by weight of a neutralizer, all % byweights based on the total weight of the waterborne polyurethane resin.

For the color coating composition, the waterborne acrylic resin may havepH of about 7 to 10 and a viscosity of about 300 to 1,000 mPa·s.

Preferably, the waterborne acrylic resin may comprise an amount of about50 to 80% by weight of a methacrylic monomer having an aliphatic group,an amount of about 5 to 20% by weight of a methacrylic monomer having ahydroxyl group, an amount of about 3 to 10% by weight of a methacrylicmonomer having an acid radical, and an amount of about 10 to 20% byweight of an acrylic monomer, all the % by weight based on the totalweight of the waterborne acrylic resin.

For the color coating composition, an average particle size of thecoloring pigment may suitably be of about 1 to 10 μm.

For the color coating composition, the wetting agent may be one or moreselected from the group consisting of siloxane modified with polyether,a polyether-siloxane copolymer, polydimethyl siloxane, andpolydimethylsiloxane modified with polyether.

For the color coating composition, the hardening accelerator may be oneor more selected from the group consisting of trimethylene diamine,stannous octoate, dibutyltin dilaurate, and lead 2-ethylhexonate.

For the color coating composition, the light stabilizer may suitably beone or more selected from the group consisting of benzophenones,oxanilides, benzotriazoles, triazines,4-benzoyloxy-2,2,6,6-tetramethylpiperidin, and2,4-di-tert-butylphenyl-3,5-di-tert-butyl-hydroxybenzoid.

For the color coating composition, the thickener may be one or moreselected from the group consisting of acrylic thickeners, urethane, andethylene-vinyl acetate.

In addition, for the clear coating composition, the acrylic resin maysuitably have an acid value of about 3 to 10 mg/KOH, may comprise ahydroxyl group in a content of about 1 to 3%, and may suitably have aglass transition temperature of about 40 to 50° C. and a weight-averagemolecular weight (Mw) of about 6,000 to 15,000.

For the clear coating composition, the polyester polyol may comprise ahydroxyl group in a content of about 4 to 6% and suitably may have aweight-average molecular weight (Mw) of about 3,000 to 10,000.

For the clear coating composition, the reaction catalyst may preferablybe dibutyltin dilaurate.

For the clear coating composition, the wetting additive may preferablybe a polydimethylsiloxane-based material.

In another aspect, provided is a method of producing a multilayercoating film. In an exemplary embodiment, the method may comprise:providing a cork layer; coating a color coating composition on the corklayer to form a color coating film; and coating a clear coatingcomposition on the color coating film to form a clear coating film.Particularly, the color coating composition may comprise an amount ofabout 30 to 50% by weight of the waterborne polyurethane resin, anamount of about 10 to 30% by weight of the waterborne acrylic resin, anamount of about 0.3 to 5% by weight of the coloring pigment, an amountof about 0.1 to 1.0% by weight of the wetting agent, an amount of about0.1 to 2.0% by weight of the defoaming agent, an amount of about 0.01 to1.0% by weight of the hardening accelerator, an amount of about 0.5 to5.0% by weight of the light stabilizer , an amount of about 0.1 to 3.0%by weight of the thickener, and an amount of about 5 to 30% by weight ofthe solvent, all the % by weight based on the total weight of the colorcoating composition. In addition, the clear coating composition maycomprise an amount of about 20 to 40% by weight of the acrylic resin, anamount of about 5 to 15% by weight of the polyester polyol, an amount ofabout 0.1 to 1.5% by weight of the reaction catalyst, an amount of about0.1 to 1.0% by weight of the wetting additive, an amount of about 1.0 to2.0% by weight of the light stabilizer, an amount of about 1.0 to 5.0%by weight of the quencher, an amount of about 10 to 20% by weight of thehardener, and an amount of about 25 to 30% by weight of the solvent, allthe % by weight based on the total weight of the clear coatingcomposition.

Preferably, a thickness of the color coating film may be of about 5 to10 μm and a thickness of the clear coating film may be of about 25 to 35μm.

Further provided in the present invention is a vehicle that may comprisethe multilayer coating film as described herein.

Other aspects and preferred embodiments of the invention are discussedinfra.

DETAILED DESCRIPTION

The terminology used herein is for the purpose of describing particularexemplary embodiments only and is not intended to be limiting of theinvention. As used herein, the singular forms “a”, “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will be further understood that the terms“comprises” and/or “comprising,” when used in this specification,specify the presence of stated features, integers, steps, operations,elements, and/or components, but do not preclude the presence oraddition of one or more other features, integers, steps, operations,elements, components, and/or groups thereof. As used herein, the term“and/or” includes any and all combinations of one or more of theassociated listed items.

Unless specifically stated or obvious from context, as used herein, theterm “about” is understood as within a range of normal tolerance in theart, for example within 2 standard deviations of the mean. “About” canbe understood as within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%,0.1%, 0.05%, or 0.01% of the stated value. Unless otherwise clear fromthe context, all numerical values provided herein are modified by theterm “about.”

It is understood that the term “vehicle” or “vehicular” or other similarterm as used herein is inclusive of motor vehicles in general such aspassenger automobiles including sports utility vehicles (SUV), buses,trucks, various commercial vehicles, watercraft including a variety ofboats and ships, aircraft, and the like, and includes hybrid vehicles,electric vehicles, plug-in hybrid electric vehicles, hydrogen-poweredvehicles and other alternative fuel vehicles (e.g. fuels derived fromresources other than petroleum). As referred to herein, a hybrid vehicleis a vehicle that has two or more sources of power, for example bothgasoline-powered and electric-powered vehicles.

Hereinafter reference will now be made in detail to various exemplaryembodiments of the present invention, examples of which are illustratedin the accompanying drawings and described below. While the inventionwill be described in conjunction with exemplary embodiments, it will beunderstood that present description is not intended to limit theinvention to those exemplary embodiments. On the contrary, the inventionis intended to cover not only the exemplary embodiments, but alsovarious alternatives, modifications, equivalents and other embodiments,which may be included within the spirit and scope of the invention asdefined by the appended claims.

The present invention provides a multilayer coating film made from anatural material using a natural cork material including a base layer, anon-woven fabric layer, and a cork layer, and a method of producing thesame.

The multilayer coating film may include a base layer, a non-woven fabriclayer, and a cork layer that may comprise a color coating composition onthe cork layer to form a color coating film; and coating a clear coatingcomposition on the color coating film to form a clear coating film. Inparticular, the color coating composition may include a waterbornepolyurethane resin, a waterborne acrylic resin, a coloring pigment, awetting agent, a defoaming agent, a hardening accelerator, a lightstabilizer, a thickener, and a solvent, and the clear coatingcomposition may comprise an acrylic resin, a polyester polyol, areaction catalyst, a wetting additive, a light stabilizer, a quencher, ahardener, and a solvent.

In particular, the multilayer coating film according to the presentinvention may comprise the color coating film such that the color ofcork may be diversified and discoloration due to vulnerability to light(UV light, etc.) may be prevented. In addition, since a surface of thenatural material may be protected by the clear coating film, durabilityagainst scratches, abrasion, and the like may be increased. In addition,surface gloss may be controlled, and various appearances may beobtained.

Preferably, the thickness of the color coating film may be of about 5 to10 μm and the thickness of the clear coating film may be f\of about 25to 35 μm. In particular, when the thickness of the color coating film isless than about 5 μm, light resistance may not be secured. When thethickness of the color coating film is greater than about 10 μm, uniquecork decoration is concealed and thus characteristics of the corkmaterial may be damaged. In addition, when the thickness of the clearcoating film is less than about 25 μm, reliability may not be secured.When the thickness of the clear coating film is greater than about 35μm, clear gloss may increase and thus the characteristics of the corkmaterial may be damaged.

Preferably, when the clear coating film is formed, the clear coating maybe performed twice or greater times to form a multilayer clear coatingfilm. When the clear coating is performed once, surface performance maybe decreased because the cork layer material absorbs the clear coatingcomposition. Therefore, the clear coating may be preferably performedtwice or greater times.

Preferably, the color coating composition may include an amount of about30 to 50% by weight of the waterborne polyurethane resin, an amount ofabout 10 to 30% by weight of the waterborne acrylic resin, an amount ofabout 0.3 to 5% by weight of the coloring pigment, an amount of about0.1 to 1.0% by weight of the wetting agent, an amount of about 0.1 to2.0% by weight of the defoaming agent, an amount of about 0.01 to 1.0%by weight of the hardening accelerator, an amount of about 0.5 to 5.0%by weight of the light stabilizer, an amount of about 0.1 to 3.0% byweight of the thickener, and an amount of about 5 to 30% by weight ofthe solvent. All the % by weight are based on the total weight of thecolor coating composition.

The waterborne polyurethane resin as used herein may provide flexibilityand particularly impact resistance and adhesion. In the waterbornepolyurethane resin, the content of solid may be in an amount of about 20to 40% by weight, or particularly an amount of about 30% by weight basedon the total weight of the waterborne polyurethane resin. In addition,pH of the waterborne polyurethane resin may be of about 6 to 10, or ofabout 7.5 to 8.5. Further, the waterborne polyurethane resin may have atensile strength of about 5 to 35 mPa and a fracture elongation of about600 to 800%.

In addition, the waterborne polyurethane resin may be used in an amountof 30 to 50% by weight based on the total of the color coatingcomposition. When the content of the waterborne polyurethane resin isless than about 30% by weight, coating film properties such as adhesionand sunscreen resistance may deteriorate. When the content of thewaterborne polyurethane resin is greater than about 50% by weight,coating workability may be decreased due to a resin with high molecularweight, and thus, appearance deteriorates.

Preferably, the waterborne polyurethane resin may include an amount ofabout 5 to 30% by weight of isocyanate, an amount of about 2 to 10% byweight of hydrophilic polyol, an amount of about 30 to 60% by weight ofpolycarbonate diol, an amount of about 5 to 25% by weight of a solvent,and an amount of about 1 to 5% by weight of a neutralizer, based on thetotal weight of the waterborne polyurethane resin.

Preferably, the number of functional groups of the isocyanate may be twoor greater on average. The isocyanate may include one or more selectedfrom toluene diisocyanate, 4,4-diphenyl methane diisocyanate,hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethanediisocyanate, and polyfunctional isocyanates, or derivatives thereof.Preferably, the isocyanate may be isophorone diisocyanate,dicyclohexylmethane diisocyanate, or a mixture thereof.

The number of functional groups of the hydrophilic polyol may be two orgreater on average. The hydrophilic polyol as used herein may providehydrophilicity to a urethane chain to facilitate water dispersion. Thehydrophilic polyol may include one or more selected fromdimethylpropionic acid, dimethylbutanoic acid, polyoxyethylene glycol,polycaprolactone diol having a carboxylic group at a side chain thereof,polyether diol having a sulfonic acid group at a side chain thereof,polyol having a polyoxyethylene group substituted with an alkoxy groupat a side chain thereof, and carbonate diol. In particular, when thepolycarbonate diol has a weight-average molecular weight (Mw) of 500 to5,000, impact resistance and adhesion may be advantageously secured.

Preferably, the waterborne acrylic resin may be prepared by preparing apolymer through radical-polymerization of various monomers having avinyl-type double bond of acrylic ester or methacrylic ester in asolution using a thermal decomposition initiator and then neutralizingacidity with amine, and the like followed by dispersing the polymer inwater.

In addition, the waterborne acrylic resin with low viscosity may providesuperior workability upon coating, adhesion, moisture resistance, andlight resistance. In the waterborne acrylic resin, the content of asolid may be of about 50% by weight. In addition, the waterborne acrylicresin may have pH of about 7 to 10 and a viscosity of about 300 to 1,000mPa·s. The waterborne acrylic resin may be used as a one-componentlacquer not including a hardener. The waterborne acrylic resin may beused in an amount of about 10 to 30% by weight based on the total of thecolor coating composition. When the content of the waterborne acrylicresin is less than about 10% by weight, coating film properties such asadhesion, sunscreen resistance, and light resistance may deteriorate.When the content of the waterborne acrylic resin is greater than about30% by weight, impact resistance may be decreased.

Preferably, the waterborne acrylic resin may include an amount of about50 to 80% by weight of a methacrylic monomer having an aliphatic group,an amount of about 5 to 20% by weight of a methacrylic monomer having ahydroxyl group, an amount of about 3 to 10% by weight of a methacrylicmonomer having an acid radical, and an amount of about 10 to 20% byweight of an acrylic monomer, based on the total weight of thewaterborne acrylic resin.

The methacrylic monomer having an aliphatic group may include one ormore selected from the group consisting of butylmethacrylate,methylmethacrylate, ethylmethacrylate, 2-ethylhexylmethacrylate,laurylmethacrylate, isobornyl methacrylate, and cyclohexyl methacrylatemay be used. In addition, the acrylic monomer having an aliphatic groupmay be butylacrylate, ethylacrylate, 2-ethylhexylacrylate, or a mixturethereof.

In addition, the methacrylic monomer having a hydroxyl group may be2-hydroxyethylmethacrylate, 2-hydroxypropylmethacrylate, or a mixturethereof, and the methacrylic monomer having a carboxylic group may bemethacrylate. In addition, the radical initiator may include one or moreselected from the group consisting of t-butylperoxybenzoate,t-butylperoxy-2-ethylhexanoate and t-amylperoxy-2-ethylhexanoate. Inaddition, a polymerizable radical initiator as an organic peroxide maybe used alone or a mixture of two or more polymerizable radicalinitiators may be used. In addition, the amine may beN-methyldiethanolamine, triethanolamine, or the like.

For example, the methacrylic monomer with an aliphatic group, themethacrylic monomer having a hydroxyl group, and the acrylic monomerinitiator may be polymerized at a temperature of about 100 to 130° C.for about 8 to 11 hours while adding dropwise over about 2 to 5 hours inthe aforementioned composition ratio. Subsequently, a resultant productis cooled to a temperature of about 70° C. or less and then amine may befed thereinto, followed by maintaining a reaction state for about 30minutes to 1 hour. Subsequently, a resultant product may be dispersed inwater.

Preferably, an average particle size of the coloring pigment may be ofabout 1 to 10 μm which may have a size less than those of conventionalpigments. In addition, since the coloring pigment may have high coloringstrength and superior penetrability, patterns of the cork material maybe easily highlighted. When the coloring pigment has an average particlesize of less than about 1 μm, transparency may be decreased. When thecoloring pigment has an average particle size of greater than about 10μm, stains may be generated during coating. The coloring pigment has anaverage particle size of about 1 to 5 μm, or particularly of about 3 μm.

In addition, the coloring pigment may be used in an amount of about 0.3to 5% by weight based on a total of the color coating composition. Whenthe content of the coloring pigment is less than about 0.3% by weight,color is not easily realized. When the content of the coloring pigmentis greater than about 5% by weight, concealment force increases and thusunique patterns of the material may not be sufficiently obtained.

The wetting agent as used herein may increase wettability by decreasingthe surface tension of water based paint, prevents cratering, andprovides a slip property to a surface. The wetting agent may include oneor more selected from the group consisting of siloxane modified withpolyether, a polyether-siloxane copolymer, polydimethyl siloxane, andpolydimethylsiloxane modified with polyether.

The defoaming agent as used herein may be a non-silicon-based agent andmay prevent appearance defects by destroying bubbles during coatingmaterial preparation and coating. The defoaming agent may be used in anamount of about 0.1 to 2.0% by weight based on the total of the colorcoating composition. When the content of the defoaming agent is lessthan about 0.1% by weight, defoaming effects may not be sufficient. Whenthe content of the defoaming agent is greater than about 2.0% by weight,adhesion may be decreased upon re-coating.

The hardening accelerator may include one or more selected from thegroup consisting of trimethylene diamine, stannous octoate, dibutyltindilaurate, and lead 2-ethylhexonate. The hardening accelerator as aurethane reaction catalyst may increase a reaction rate between a mainmaterial (hydroxyl group) and a hardener (isocyanate). When thehardening accelerator is added in a greater than the predeterminedamount, for example, greater than about 1% by weight based on the totalweight of the color coating composition, pot life may be decreased andthus workability may be decreased.

The light stabilizer may be one or more selected from the groupconsisting of benzophenones, oxanilides, benzotriazole, triazine,4-benzoyloxy-2,2,6,6-tetramethylpiperidine, and2,4-di-tert-butylphenyl-3,5-di-tert-butyl-hydroxybenzoid. The lightstabilizer prevents aging, color change, and the like of a coating filmdue to long-term exposure to light.

The thickener may prevent precipitation during storage of a coatingmaterial and may effectively prevent flowing of a coating materialduring coating. The thickener may be one or more selected from the groupconsisting of acrylic thickeners, urethane, and ethylene-vinyl acetate.

The solvent may be preferably distilled water. When distilled water isused as the solvent, viscosity may be controlled during coating and thuscoating workability may be enhanced.

Preferably, the clear coating composition may include an amount of about20 to 40% by weight of the acrylic resin, an amount of about 5 to 15% byweight of the polyester polyol, an amount of about 0.1 to 1.5% by weightof the reaction catalyst, an amount of about 0.1 to 1.0% by weight ofthe wetting additive, an amount of about 1.0 to 2.0% by weight of thelight stabilizer, an amount of about 1.0 to 5.0% by weight of thequencher, an amount of about 10 to 20% by weight of the hardener, and anamount of about 25 to 30% by weight of the solvent, all the % by weightbased on the total weight of the clear coating composition.

The acrylic resin may include a solid in an amount of about 60% byweight or greater, may have an acid value of about 3 to 10 mg/KOH, mayinclude a hydroxyl group in an amount of about 1 to 3%, and may have aglass transition temperature of about 40 to 50° C. to minimizestickiness of a coating film. In addition, the acrylic resin may have aweight-average molecular weight (Mw) of about 6,000 to 15,000. Theacrylic resin may be used in an amount of about 20 to 40% by weightbased on the total of the clear coating composition. When the content ofthe acrylic resin is less than about 20% by weight, chemical resistance(sunscreen resistance) and a thermal cycle of a formed coating film maybe decreased. When the content of the acrylic resin is greater thanabout 40% by weight, flexibility and impact resistance may be decreasedand particularly a coating film may crack due to lack of flexibility.

The acrylic resin may be prepared in a polymer by radical-polymerizingvarious monomers having a double bond such as an acrylic monomer and avinyl-based monomer in a solution using a thermal decompositioninitiator. In particular, the acrylic or vinyl-based monomer may be anon-functional monomer, e.g., methylacrylate, ethylacrylate,isopropylacrylate, N-butylacrylate, ethylhexylacrylate,methylmethacrylate, ethylmethacrylate, butylmethacrylate,hexylmethacrylate, lauryl methacrylate, and the like. In addition,examples of a monomer having a carboxyl functional group may includeacrylic acid, methacrylic acid, maleic acid, itaconic acid, chronicacid, and the like. Examples of a monomer having a hydroxyl group mayinclude 2-hydroxymethacrylate, hydroxypropylacrylate,4-hydroxybutylacrylate, 2-hydroxyethylacrylate, and the like. Inaddition, examples of a vinyl-based monomer may include acrylamide,N-methylolacrylamide, glycidylmethacrylate, styrene, vinyl toluene,acrylonitrile, vinyl acetate, and the like.

The polyester polyol may include a solid in a content of about 80% byweight and a hydroxyl group in a content of about 4 to 6%, and may havea weight-average molecular weight (Mw) of about 3,000 to 10,000. Sincethe polyester polyol may have a relatively large hydroxyl group,crosslinking density may increase when reacting with isocyanate and thusmoisture resistance may be supplemented. The polyester polyol may beused in an amount of about 5 to 15% by weight based on a total of theclear coating composition. When the content of polyester polyol is lessthan about 5% by weight, moisture resistance may be slightly enhanced.When the content of polyester polyol is greater than about 15% byweight, hardness of the coating film may be decreased and surfacestickiness may occur.

The polyester polyol may be esterified. For example, an acidicingredient, a polyhydric alcohol ingredient, a catalyst, and variousadditives may be added to a reactor equipped with a stirrer. Whilemaintaining the reactor at a temperature of about 200 to 230° C., acondensed low-molecular-weight ester byproduct may be removed to theoutside and, at the same time, the polyester polyol may be esterified.Here, the reaction may terminated based on a time point when aconversion rate in the esterification is generally about 95% or greaterbased on a theoretical outflow amount of the low-molecular-weight esterbyproduct. When esterification is terminated, polyester condensationreaction may be induced while elevating the temperature of the reactorto a temperature of about 250 to 280° C. This condensation reaction maybe terminated when an acid value is about 2 to 4 mg KOH/g or less. As aresult, a polyester resin may be produced.

Preferably, the reaction catalyst may be dibutyltin dilaurate.

Preferably, the wetting additive may be a polydimethylsiloxane-basedsubstance as a substance to enhance wettability during coating andleveling properties of a coating film.

The light stabilizer may be a UV absorbent and may increase lightresistance. The light stabilizer may preferably be a mixture of UVA(benzophenone group or triazole group) and HALS(4-amino-2,2,6,6-tetramethyl piperidine or 4-hydroxy-2,2,6,6-tetramethylpiperidine).

The quencher may suitably have a particle size of about 1.0 to 2.0 μm,and may have superior penetrability, and hydrophobic properties.Accordingly, the quencher as used herein may not absorb moisture,thereby having superior moisture resistance. In addition, when subjectedto a flexibility test, the coating film may not be whitened due to smallparticles of the quencher. When the particle size of the quencher isless than about 1% by weight, quenching effects may not be expected.When the particle size of the quencher is greater than about 5% byweight, gloss may be reduced and thus the characteristics of the corkmaterial may not remain.

The hardener may preferably be a hexamethylene diisocyanate trimerhaving superior non-yellowing properties and weather resistance.

The solvent may be preferably an ester-based solvent, a ketone-basedsolvent, or a mixture thereof, and the solvent, may exclude ahydrocarbon-based substance. The solvent as used herein may facilitatecoating. In addition, the smoothness and appearance of the coating filmmay be controlled by adjusting the volatilization rate of the solvent.

The method of producing the multilayer coating film as described hereinmay comprise: providing a cork layer; coating a color coatingcomposition on the cork layer to form a color coating film; and coatinga clear coating composition on the color coating film to form a clearcoating film.

Particularly, In particular, the color coating composition may include awaterborne polyurethane resin, a waterborne acrylic resin, a coloringpigment, a wetting agent, a defoaming agent, a hardening accelerator, alight stabilizer, a thickener, and a solvent, and the clear coatingcomposition may comprise an acrylic resin, a polyester polyol, areaction catalyst, a wetting additive, a light stabilizer, a quencher, ahardener, and a solvent. Contents of the components are described above.

Preferably, a thickness of the color coating film may be of about 5 to10 μm and a thickness of the clear coating film may be of about 25 to 35μm.

According to various exemplary embodiments of the present invention, themultilayer coating film made from a natural material may providediversified color and gloss of the cork as the natural material. Themethod of producing the multilayer coating film may include, inparticular, forming the color coating film, which provides adhesion tothe cork material and color, on the cork material and forming the clearcoating film, which provides texture and supplement property, on thecolor coating film. As such, the multilayer coating film and the methodof producing thereof as described herein may increase marketability ofan interior material and realize various appearance effects.

In addition, the multilayer coating film may be formed by using thecolor coating composition and the clear coating composition, which maybe suitably prepared through mixing of the components in exemplaryratio, discoloration, water permeation, and the like due to light (e.g.,UV light) may be prevented and durability against abrasion, scratches,and the like may be enhanced.

EXAMPLES

The following examples illustrate the invention and are not intended tolimit the same.

Example 1

Using ingredients in ratios summarized in the following Table 1, a colorcoating composition and a clear coating composition (two-componentoil-based compositions) were prepared according to a general method. Inparticular, the color coating composition was a liquid-type water-basedcoating material, and the viscosity thereof was adjusted using water, asa diluent, without a hardener.

In addition, a base layer (lower layer), a non-woven fabric layer(middle layer), and a cork layer (upper layer) were sequentially stackedto manufacture a film made from a natural material.

Subsequently, the upper layer, i.e., the cork layer, of the film madefrom the natural material was spray-coated with the color coatingcomposition. In particular, the viscosity of the color coatingcomposition was adjusted to about 15.0 to 17.0 sec (FordCup #4) and thenthe color coating was spray-coated to form a color coating layer havinga thickness of about 10 μm. Next, the color coating film was dried atroom temperature for 10 minutes.

Subsequently, the viscosity of the clear coating composition was dilutedto about 13.0 to 15.0 sec (FordCup #4) with a solvent and thenspray-coated on the color coating film, thereby forming a first clearcoating film with a thickness of 30 μm. Next, the first clear coatingfilm was dried at a temperature of 80° C. for 30 minutes. Subsequently,the clear coating composition was coated on the first clear coating filmaccording to the aforementioned method, thereby forming a second clearcoating film. Subsequently, secondary drying was performed at atemperature of 80° C. for 30 minutes. With regard to hardening (coatingfilm formation), a 3 coat 2 baking system was applied.

Composition

(1) Color Coating Composition

1) Waterborne polyurethane including 15% by weight of isocyanate, 7% byweight of hydrophilic polyol, 50% by weight of polycarbonate diol, 25%by weight of solvent, and 3% by weight of neutralizer based on the totalweight of the waterborne polyurethane (manufactured by NRB)

2) Waterborne acrylic resin including 71% by weight of methacrylicmonomer with an aliphatic group, 9% by weight of methacrylic monomerwith a hydroxyl group, 5% by weight of methacrylic monomer with an acidradical, 12% by weight of acrylic monomer, 2% by weight of initiator,and 1% by weight of amine, based on the total weight of the waterborneacryl resin, and having 50% by weight of solid, pH of 8, and a viscosityof 1,000 to 1,200 mPa·s (manufactured by NRB)

3) Coloring Pigment having an average particle size of 5 μm, andMICROLIPH was used (manufactured by BASF).

4) As other additives of the color coating composition, 1% by weight ofwetting agent, 2% by weight of defoaming agent, 1% by weight ofhardening accelerator, 5% by weight of light stabilizer, and 3% byweight of thickener were added. The content of a solvent was controlleddepending upon of the content of the coloring pigment such that thetotal amount of the color coating composition was 100% by weight.

(2) Clear Coating Composition

1) Acrylic resin: N3-0540(manufactured by NRB)

2) Polyester polyol: K6-0670(manufactured by NRB)

3) Hydrophobic quencher: Hydrophobic silica with an average particlesize of 1.0 to 2.0 μm was used

4) As other additives of the clear coating composition, 1.5% by weightof reaction catalyst (dibutyltin dilaurate), 1% by weight of wettingadditive (BYK-306), 2% by weight of light stabilizer (mixture of Tinuvin479 (UVA) and Tinuvin 1130 (UVA)), and 20% by weight of hardener(HI-100, manufactured by BASF) were added. The amount of a solvent wasadjusted depending upon the content of the hydrophobic quencher suchthat the total amount of the clear coating composition was 100% byweight.

Example 2 and Comparative Examples 1 to 9

Components and ratios summarized in the following Table 1 were used, anda multilayer coating film including a color coating film and a clearcoating film was formed on a cork layer of a natural material film inthe same manner as in Example 1.

TABLE 1 Ingredients Color coating composition Clear coating composition(coating once in total) (coating twice in total) Waterborne WaterborneColoring Acrylic Polyester Hydrophobic Classification polyurethaneacrylic resin pigment resin polyol quencher Three-layer Comparative 2040 1 15 30 3 coat Example 1 Comparative 60  0 1 45  0 3 Example 2Comparative 40 20 — 30 15 3 Example 3 Comparative 40 20 6 30 15 3Example 4 Comparative 40 20 1 15 30 3 Example 5 Comparative 40 20 1 3015 — Example 6 Comparative 40 20 1 30 15 6 Example 7 Comparative 40 20 1— — — Example 8 Comparative — — — 30 15 3 Example 9 Example 1 40 20 1 3015 3 Example 2 30 30 1 40  5 3

EXPERIMENTAL EXAMPLE

Properties such as initial adhesion, impact resistance, sunscreenresistance, heat-resistance, moisture resistance, and light resistanceof the natural material films having the multilayer coating film formedthereon manufactured according to Examples 1 and 2 and ComparativeExamples 1 to 9 were evaluated. Results are summarized in Table 2 below.

[Measurement Methods]

(1) Appearance of cork material: The patterns of the cork material wereobserved with the naked eye after the color coating (Levels 1 to 5),Level 1 (patterns are not shown), Level 5 (clear patterns areobserved)→Level 4 or more were determined to be satisfactory.

(2) Gloss: Measured at 60° using a gloss meter manufactured by BYKGARDNER. When gloss was 5.0 or greater, the unique texture of cork wasdecreased due to high gloss. When gloss is 3.0 or less, strong quenchingeffect was exhibited and thus the texture of cork was not felt.

(3) Initial adhesion: Dotted lines were drawn across a coating filmsurface with a cutter such that the dotted lines were also drawn acrossa base material, thereby preparing 100 square cells with a size of 2mm×2 mm. An adhesive cellophane tape was attached to the square cellsand then it was rapidly peeled from the square cells at 90°.Subsequently, the number of the coating films remaining in the cells wasevaluated.

(4) Impact resistance: A 0.5 Kg weight was dropped from a height of 20cm by means of an ISO 6272 falling weight sensitivity tester to evaluatebreakage and appearance of a coating film.

(5) Sunscreen resistance: The natural material film was coated withpredetermined sunscreen and then stood at a temperature of 80° C. in anoven for one hour. The natural material film was taken out of the ovenand subjected to appearance evaluation and adhesion tests.

(6) Heat resistance: A test piece was stood at a temperature of a 90±2°C. in a chamber for 300 hours. Subsequently, the test pieces were takenout of the chamber and subjected to appearance evaluation and adhesiontests.

(7) Moisture resistance: A test piece was stood for 240 hours in achamber with a test temperature of 50±2° C. and a relative humidity of95±2% RH. Subsequently, the test piece was taken out of the chamber andsubjected to appearance evaluation and initial adhesion tests.

(8) Light resistance: Light was irradiated to a coating specimen until atotal accumulated light amount was 700 kJ/m² using a xenon arc lampunder conditions of a black panel temperature of 89±3° C., an interiorhumidity of 50±5% RH, and an irradiation illumination of 0.55±0.02 W/m²(340 nm). Subsequently, the specimen was taken out of the xenon arc lampand washed with a neutral aqueous detergent. The washed specimen wasdried and subjected to appearance evaluation and initial adhesion tests.

(※ Gray scale: Level 1 (discoloration is severe, bad) to 5 (Nodiscoloration, good))

TABLE 2 Cork material Initial Impact Sunscreen Heat- Moisture LightClassification pattern Gloss adhesion resistance resistance resistanceresistance resistance Three- Comparative 4 3.5  90/100 N.G N.G N.G N.GN.G layer Example 1 (broken) (peeled) (peeled) (peeled) (peeled) coatComparative 4 3.5  80/100 N.G N.G N.G N.G N.G Example 2 (broken)(peeled) (peeled) (peeled) (peeled) Comparative 5 3.5 100/100Satisfactory Satisfactory Satisfactory Satisfactory N.G Example 3(discoloration, Level 1) Comparative 1 3.0 100/100 SatisfactorySatisfactory Satisfactory Satisfactory Level 4 Example 4 Comparative 43.5 100/100 Satisfactory N.G Satisfactory N.G N.G Example 5 (swelled)(discoloration, Level 2) Comparative 4 85 100/100 SatisfactorySatisfactory Satisfactory Satisfactory Level 3 Example 6 Comparative 21.0 100/100 N.G Satisfactory Satisfactory Satisfactory N.G Example 7(whitened) Level 3 Comparative 4 35 100/100 Satisfactory N.GSatisfactory Satisfactory N.G Example 8 (discoloration) (discoloration,Level 2) Comparative 5 3.5 N.G Satisfactory N.G N.G N.G N.G Example 9(peeled) (swelled) (peeled) (peeled) (peeled) Example 1 4 3.5 100/100Satisfactory Satisfactory Satisfactory Satisfactory Level 5 Example 2 43.5 100/100 Satisfactory Satisfactory Satisfactory Satisfactory Level 5

As shown in Table 2, it can be confirmed that, in the case ofComparative Example 1 in which the content of the waterbornepolyurethane in the color coating composition and the content of theacrylic resin in clear coating composition were low, initial adhesionwas not expressed, the results of the tests related to adhesion(sunscreen resistance, heat-resistance, moisture resistance, and lightresistance) were all poor, and, the coating film was broken after impactsince hardness increased when the content of the waterborne acrylicresin increased.

In addition, it can be confirmed that, in the case of ComparativeExample 2 in which the content of the waterborne polyurethane in thecolor coating composition and the content of the acrylic resin in theclear coating composition were high, initial adhesion was not expressed,and the results of tests for evaluating adhesion (sunscreen resistance,heat-resistance, moisture resistance, and light resistance) were allunsatisfactory. In particular, it can be confirmed that, when thecontent of the acryl used in the clear coating composition was high, abreakage phenomenon occurred in an impact resistance evaluation test.

In addition, it can be confirmed that, in the case of ComparativeExample 3 in which the coloring pigment was not used in the colorcoating composition, the clearest cork patterns were exhibited, but thepoorest discoloration was exhibited in the light resistance test.

In addition, it can be confirmed that, in the case of ComparativeExample 4 in which the content of the coloring pigment was high in thecolor coating composition, lowest discoloration was exhibited in thelight resistance test, but cork patterns were concealed due to increasedconcealment force, whereby the texture of cork, as a natural material,was decreased.

In addition, it can be confirmed that, in the case of ComparativeExample 5 in which the content of the color coating composition wasproper and the content of the polyester in the clear coating compositionincreases, sunscreen resistance was decreased.

In addition, it can be confirmed that, in the case of ComparativeExample 6 in which the content of the hydrophobic quencher in the clearcoating composition was low or the hydrophobic quencher was not used inthe clear coating composition, gloss increased and thus natural corkfeeling decreased.

In addition, it can be confirmed that, in the case of ComparativeExample 7 in which the content of the hydrophobic quencher used in theclear coating composition was increased, gloss was too low and thus corkfeeling was decreased due to rough texture. Here, a gloss range in whichfeeling of a natural cork material was exhibited is 3.0 to 4.0 (60degree). In addition, it can be confirmed that, when the quencher wasused in an excessively large amount or a quencher with a large particlesize is used, whitening occurred after the impact resistance evaluation.

Further, in the cases of Comparative Examples 8 and 9 in which the colorcoating film or the clear coating film was respectively, separatelyformed, sunscreen resistance and light resistance were poor when onlythe color coating film was coated, and adhesion to the material was notgood when only the clear coating film was coated.

On the other hand, it can be confirmed that, in the cases of Examples 1and 2, properties such as adhesion were satisfied when the waterbornepolyurethane and the waterborne acrylic resin were used within theaforementioned range in the color coating composition, and lightresistance was satisfied without deterioration of natural cork feelingwhen the coloring pigment was used. In addition, in the case of clearcoating composition, sunscreen resistance, heat-resistance, moistureresistance, and light resistance were satisfied when the newlysynthesized acrylic resin and the polyester polyols were used within theaforementioned range, and realization of natural cork feeling weremaximized when the hydrophobic quencher was used.

Therefore, it can be confirmed that, by applying the color coating filmto the natural material film having the multilayer coating filmmanufactured according to Examples 1 and 2, the color of the cork may bediversified, and discoloration of the natural film material due tovulnerability to light (UV light, etc.) may be prevented. In addition,since a surface of the natural material film is protected by applyingthe clear coating film, durability against scratches, abrasion and thelike may be increased. In addition, gloss may be controlled, therebyrealizing various appearance effects.

As apparently demonstrated from the foregoing, the present inventionadvantageously provides a multilayer coating film and a method offorming the multilayer coating film made from a natural material todiversify the color and gloss of cork as a natural material. Inaddition, the multilayer coating film may obtain a marketabilityincrease of an interior material and provide various appearances to theinterior material, by forming the multilayer coating film throughformation of a color coating film for providing adhesion and color to acork on the cork material and a clear coating film for realizing textureand supplementing properties on the color coating film.

In addition, by respectively using the color coating composition andclear coating composition prepared by mixing the components above insuitable content ratio, the multilayer coating film may be formed. Thismultilayer coating film may prevent discoloration due to light (e.g. UVlight), water permeation and the like and may enhance durability againstabrasion, scratches and the like.

The invention has been described in detail with reference to variousexemplary embodiments thereof. However, it will be appreciated by thoseskilled in the art that changes may be made in these embodiments withoutdeparting from the principles and spirit of the invention, the scope ofwhich is defined in the appended claims and their equivalents.

1. A multilayer coating film comprising: a base layer, a non-wovenfabric layer, and a cork layer comprising a color coating compositionand a clear coating composition, wherein the color coating compositionis coated on the cork layer to form a color coating film and the clearcoating composition is coated on the color coating film to form a clearcoating film, wherein the color coating composition comprises awaterborne polyurethane resin, a waterborne acrylic resin, a coloringpigment, a wetting agent, a defoaming agent, a hardening accelerator, alight stabilizer, a thickener, and a solvent, and the clear coatingcomposition comprises an acrylic resin, a polyester polyol, a reactioncatalyst, a wetting additive, a light stabilizer, a quencher, ahardener, and a solvent.
 2. The multilayer coating film of claim 1,wherein a thickness of the color coating film is of about 5 to 10 μm anda thickness of the clear coating film is of about 25 to 35 μm.
 3. Themultilayer coating film of claim 1, wherein the color coatingcomposition comprises an amount of about 30 to 50% by weight of thewaterborne polyurethane resin, an amount of about 10 to 30% by weight ofthe waterborne acrylic resin, an amount of about 0.3 to 5% by weight ofthe coloring pigment, an amount of about 0.1 to 1.0% by weight of thewetting agent, an amount of about 0.1 to 2.0% by weight of the defoamingagent, an amount of about 0.01 to 1.0% by weight of the hardeningaccelerator, an amount of about 0.5 to 5.0% by weight of the lightstabilizer , an amount of about 0.1 to 3.0% by weight of the thickener,and an amount of about 5 to 30% by weight of the solvent, all the % byweight based on the total weight of the color coating composition. 4.The multilayer coating film of claim 1, wherein the clear coatingcomposition comprises an amount of about 20 to 40% by weight of theacrylic resin, an amount of about 5 to 15% by weight of the polyesterpolyol, an amount of about 0.1 to 1.5% by weight of the reactioncatalyst, an amount of about 0.1 to 1.0% by weight of the wettingadditive, an amount of about 1.0 to 2.0% by weight of the lightstabilizer, an amount of about 1.0 to 5.0% by weight of the quencher, anamount of about 10 to 20% by weight of the hardener, and an amount ofabout 25 to 30% by weight of the solvent, all the % by weight based onthe total weight of the clear coating composition.
 5. The multilayercoating film of claim 3, wherein the waterborne polyurethane resincomprises an amount of about 20 to 40% by weight of a solid contentbased on the total weight of the waterborne polyurethane resin, and thewaterborne polyurethane resin has pH of about 6 to
 10. 6. The multilayercoating film of claim 3, wherein the waterborne polyurethane resincomprises an amount of about 5 to 30% by weight of isocyanate, an amountof about 2 to 10% by weight of hydrophilic polyol, an amount of about 30to 60% by weight of polycarbonate diol, an amount of about 5 to 25% byweight of a solvent, and an amount of about 1 to 5% by weight of aneutralizer, all % by weights based on the total weight of thewaterborne polyurethane resin.
 7. The multilayer coating film of claim3, wherein the waterborne acrylic resin has pH of about 7 to 10 and aviscosity of about 300 to 1,000 mPa·s.
 8. The multilayer coating film ofclaim 3, wherein the waterborne acrylic resin comprises an amount ofabout 50 to 80% by weight of a methacrylic monomer having an aliphaticgroup, an amount of about 5 to 20% by weight of a methacrylic monomerhaving a hydroxyl group, an amount of about 3 to 10% by weight of amethacrylic monomer having an acid radical, and an amount of about 10 to20% by weight of an acrylic monomer, all the % by weight based on thetotal weight of the waterborne acrylic resin.
 9. The multilayer coatingfilm of claim 3, wherein an average particle size of the coloringpigment is of about 1 to 10 μm.
 10. The multilayer coating film of claim3, wherein the wetting agent is one or more selected from the groupconsisting of siloxane modified with polyether, a polyether-siloxanecopolymer, polydimethyl siloxane, and polydimethylsiloxane modified withpolyether.
 11. The multilayer coating film of claim 3, wherein thehardening accelerator is one or more selected from the group consistingof trimethylene diamine, stannous octoate, dibutyltin dilaurate, andlead 2-ethylhexonate.
 12. The multilayer coating film of claim 3,wherein the light stabilizer is one or more selected from the groupconsisting of benzophenones, oxanilides, benzotriazoles, triazines,4-benzoyloxy-2,2,6,6-tetramethylpiperidin, and2,4-di-tert-butylphenyl-3,5-di-tert-butyl-hydroxybenzoid.
 13. Themultilayer coating film of claim 3, wherein the thickener is one or moreselected from the group consisting of acrylic thickeners, urethane, andethylene-vinyl acetate.
 14. The multilayer coating film of claim 4,wherein the acrylic resin has an acid value of about 3 to 10 mg/KOH,comprises a hydroxyl group in a content of about 1 to 3%, and has aglass transition temperature of about 40 to 50° C. and a weight-averagemolecular weight (Mw) of about 6,000 to 15,000.
 15. The multilayercoating film of claim 4, wherein the polyester polyol comprises ahydroxyl group in a content of about 4 to 6% and has a weight-averagemolecular weight (Mw) of about 3,000 to 10,000.
 16. The multilayercoating film of claim 4, wherein the reaction catalyst is dibutyltindilaurate.
 17. The multilayer coating film of claim 4, wherein thewetting additive is a polydimethylsiloxane-based material. 18-19.(canceled)
 20. A vehicle that comprises a multilayer coating film ofclaim 1.